Battery pack, and battery system

Abstract

An object of the present invention is to provide a battery pack and a battery system capable of reducing unnecessary power loss upon reducing the variation in the state of charge that has occurred between a plurality of secondary batteries in an assembled battery in which the secondary batteries are connected in series-parallel. The battery pack and the battery system include a switching element Q11 for opening / closing the charging path of a battery pack B1, a switching element Q12 for opening / closing the discharging path of the battery pack B1, a switching element Q21 for opening / closing the charging path of a battery pack B2, and a switching element Q22 for opening / closing the discharging path of the battery pack B2. When the battery pack B1 is charged, the switching elements Q12, Q21 are turned OFF and the switching element Q11 is turned ON until the secondary batteries B11, B12 are fully charged. When the battery pack B2 is charged, the switching elements Q22, Q11 are turned OFF and the switching element Q21 is turned ON until the secondary batteries B21, B22 are fully charged.

Description

TECHNICAL FIELD [0001]The present invention relates to a battery pack in which a plurality of secondary batteries are connected in parallel, and a battery system.BACKGROUND ART [0002]When using a rechargeable battery pack including a plurality of secondary batteries connected in series as described in Patent Document 1, it is generally known that variation will arise in the quantity of accumulated charge of the batteries while they are being used, and the continued use thereof may cause only certain secondary batteries to become an overcharged state or an overdischarged state, whereby the expected life may become shortened or the secondary batteries may become an unsafe state. Thus, in order to resolve the variation in the state of charge (charging capacity) of the respective secondary batteries, a control method is known where charging is performed until the secondary battery with the smallest quantity of accumulated charge is fully charged and intentionally causing the other secon...

AI Technical Summary

Benefits of technology

"The present invention provides a battery pack and battery system that can reduce unnecessary power loss in cases where multiple secondary batteries are connected in parallel. The battery pack includes two assembled batteries, each containing multiple secondary batteries connected in series. The system includes a charge terminal, charging current supply unit, and control unit. The control unit executes first and second charge processing for each assembled battery, respectively. During the first charge processing, the control unit turns off the discharging path switch units and turns on the charging path switch units to charge all secondary batteries in the assembled battery until they are fully charged. During the second charge processing, the control unit turns off the charging path switch units and turns on the discharging path switch units to charge all secondary batteries in the second assembled battery until they are fully charged. This reduces unnecessary power loss and ensures consistent charging of all secondary batteries."

Problems solved by technology

When using a rechargeable battery pack including a plurality of secondary batteries connected in series as described in Patent Document 1, it is generally known that variation will arise in the quantity of accumulated charge of the batteries while they are being used, and the continued use thereof may cause only certain secondary batteries to become an overcharged state or an overdischarged state, whereby the expected life may become shortened or the secondary batteries may become an unsafe state.

Thus, there was an inconvenience in that unnecessary power loss will increase.Patent Document 1: Japanese Patent Application Laid-open No.

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